/Engine/Source/Runtime/Engine/Classes/Animation/BlendSpace.h
struct FBlendSpaceTriangleEdgeInfo
int32[2]
AdjacentPerimeterTriangleIndices
IF there is no neighbor, then (a) we're on the perimeter and (b) these will be the indices of triangles along the perimeter (next to the start and end of this edge, respectively)
int32[2]
AdjacentPerimeterVertexIndices
The vertex index of the associated AdjacentPerimeterTriangle such that the perimeter edge is from this vertex to the next.
int32
NeighbourTriangleIndex
FVector2D
Normal
Edge normal faces out